MINNEAPOLIS — The interstate highway bridge that collapsed into the Mississippi River had been rated "structurally deficient" for 17 years and was regularly inspected by state engineers, who spotted corroded bearings and stress fractures but remained confident that the bridge was safe, authorities said Thursday.
At least 20 vehicles remained submerged in the murky waters of the Mississippi, many of them pinned under large chunks of rubble. Divers struggled to get close, fighting strong currents and whirlpools caused by water swirling around the debris.
Authorities said it could take days, perhaps a week, before all the cars and bodies were recovered. "It's still a tremendously dangerous scene," Police Chief Tim Dolan said. Rescuers feared that moving even one piece of debris could destabilize the rubble and bring down a deadly cascade of concrete and metal.
Authorities lowered the death toll to four but said they expected the toll to rise as vehicles were lifted from the water. At least 79 people were injured, and as many as 30 others were believed missing.
As people took to the city's rooftops to get a look at the wreckage, relatives of the missing waited in numb exhaustion at the Holiday Inn Metrodome, on the north side of the river. They prayed or wept or simply dialed, calling their loved ones' cellphones again and again.
Grief counselors guided the grieving relatives past the reporters camped outside the front door, past the tourists drinking martinis in the hotel lobby. As evening fell, they tried to persuade the waiting families to go home and rest.
The collapse of the 40-year-old truss bridge followed years of warnings that it might need expensive repairs, but none of the warnings raised the prospect of the bridge failing outright.
A federal inspection in 1990 declared the Interstate 35W bridge deficient, noting a history of fractures along the plates that hold together structural arches. The bearings, which hold up the main trusses, were corroded. And the "approach spans" -- the portions of the bridge rising up from both banks -- had developed stress fractures.
Another federal inspection gave the bridge -- the busiest in the state -- 50 points out of a possible 100 for structural stability. That gave it a rating of "structurally deficient." A federal report from 2005 found about 75,000 bridges nationwide in that category -- including 1,140 other bridges in Minnesota. Authorities emphasized that such bridges do not necessarily need urgent repair and are not deemed an imminent danger.
" 'Structurally deficient' means some portions of the bridge need to be scheduled for repair or replacement. It doesn't mean that the bridge is unsafe," U.S. Transportation Secretary Mary E. Peters said.
Minnesota inspectors checked the bridge annually, taking special note of the weaknesses outlined in the federal reports. They fixed the fractures in the approach spans. But the other problems seemed relatively minor: The corroded bearings did not appear to be slipping. Stress fractures elsewhere on the bridge did not appear to be growing.
One option would have been to bolster the main arch with more steel. But some experts worried that the drilling could cause additional damage.
The engineers' conclusion: Keep a close eye. And keep traffic flowing.
The state did not anticipate replacing the bridge until at least 2015, and possibly years later. The estimated cost: $122 million.
The National Transportation Safety Board is expected to spend a year or more investigating the cause of the disaster; the board will attempt to reassemble the 458-foot span, piecing together the debris like a jigsaw puzzle.
Gov. Tim Pawlenty also has hired an outside firm to run a parallel investigation. "We want redundancy," he said.
Other officials, too, vowed to get answers.
"A bridge in America just shouldn't fall down," U.S. Sen. Amy Klobuchar (D-Minn.) said.
President Bush, who will visit the bridge site Saturday, pledged an immediate $5 million to re-route traffic and begin the cleanup, calling the bridge a "lifeline of activity." It carries about 140,000 cars a day and is a major artery for Minneapolis, connecting the two sides of the city split by the Mississippi River.
"There's going to be a lot of disruption, in terms of traffic patterns and economic activity," Pawlenty warned. Rebuilding could take up to two years -- but the governor said the federal government had pledged "unlimited money."
Minnesota's congressional delegation moved quickly on Thursday to try to make good on that promise, asking for $250 million. The House Transportation and Infrastructure Committee quickly approved the funding, but in the Senate, Majority Leader Harry Reid (D-Nev.) said it was impossible to commit so much money on such short notice. Congress adjourns Friday for its August recess.